Percussive effect for electrical music instruments



Dec. 15, 1959 HANERT 2,916,958

FERCUSSIVE EFFECT FOR ELECTRICAL MUSIC INSTRUMENTS Filed July 27, 1955 VIBRATO a 46 OSCI LLATOQR L United States Patent PERCUSSIVE EFFECT FOR ELECTRICAL MUSIC INSTRUMENTS John M. Hanert, Des Plaines, Ill., assignor to Hammond Organ Company, Chicago, 111., a corporation of Delaware Application July 27, 1955, Serial No. 524,656

' 3 Claims. (c1. 841.26)

The invention relates generally to electrical musical instruments and more particularly to an instrument of the organ type in which improved means are provided for selectively obtaining a percussion elfect in playing the instrument. An object of the invention is to provide apparatus for causing tones of an electronic organ to be soundedwith a percussion intensity envelope by playing the instrument in a non-legato manner.

Other objects will appear from the following description reference being had to the accompanying drawing in which:

Figure 1 is a schematic circuit diagram of representative portions of an electrical musical instrument incorporating the invention; and

Figure 2 is a similar diagram showing a modified form of output system of the instrument.

In Fig. 1 the instrument is illustrated as comprising a plurality of electronic oscillators 10, the three oscillators shown being representative of the sixty-one tone signal generators employed in an electronic organ of conven tional gamut. Each oscillator 10 comprises a triode 12 having a cathode 14, a control grid 16, and an anode or plate 18. The cathode 14 is connected to a tap on an inductance L20 which, with a capacitor C22, forms a resonant circuit which is mainly determinative of the frequency of oscillation of the oscillator. The values of the inductance L20 and capacitor C22 differ throughout the instrument and are such that the oscillators will oscillate at frequencies corresponding to the pitches of the semitone intervals of the musical scale. In other respects the oscillators may be substantially identical.

The control grid 16 is connected to an end terminal 24 of the inductance L20 by a capacitor C26. The plate 18 is connected to ground through a capacitor C28 to provide a by-pass for any unwanted high harmonic frequencies. Plate current is supplied to the plate 18 from a conductor 30 upon closure of a switch 32 operated by a playing key 34. The switch is connected to the plate by load resistor R36, which is in parallel with a resistor R38 the latter being in series with the capacitor C40. Plate current is supplied to the conductor 30 through the winding L42 of a relay 44, the winding L42 being connected between the conductor 30 and a terminal B+ of the power supply for the instrument. The winding L42 may be shunted by closure of a switch 45 to render the relay inoperable.

Each of the oscillators 10 has its grid 16 connected to an output conductor 46 of a vibrato apparatus 48, the connection being through a decoupling resistor R50. The circuit including the resistor R50 and vibrato oscillator 48 not only serves to vary the grid bias on the oscillator to vary its frequency of oscillation at a vibrato rate, but also provides a grid return to ground.

Signals of flute-like quality are derived from the oscillator through resistor R52 which is connected between the .endterminal 24 of the inductance L20 anda signal 2,916,958 Patented Dec. 15, 1959 are obtained through a collector conductor 54 which is connected to the other terminals 56 of the inductances L20 and is connected to ground by a load impedance R57, illustrated as a resistor.

The conductor 54 is adapted to be connected to an output conductor 58 through a decoupling resistor R62 upon closure of a manually operated switch 60. Similarly, the flute-like tone signals appearing upon the conductor 53 are transmitted to the output conductor 58 through a decoupling resistor R66 upon closure of a manually operable switch 64.

The conductor 58 is connected to ground through the primary winding L68 of an output transformer 70. The secondary winding L72 of this transformer has its end terminals connected respectively to the control grids of push pull triodes 74 and 76. The cathodes of these triodes are shown as connected to ground and their plates connected to the end terminals of a primary winding L78 of a transformer 80. The secondary L82 of this transformer is connected to a speaker 84.

The triodes 74 and 76 are normally biased so that these triodes are fully conducting, such bias being provided from a terminal 86 of the power supply on which is maintained a fixed potential which when impressed upon the control grids of triodes 74 and 76 renders these triodes conductive of the signal derived from the secondary winding L72. The connection of terminal 86 to the control grids of triodes 74 and 76 is through a contactor 88, forming a part of the relay 44, which is normally in (full line) closed position, and a resistor R90 which is connected to a center tap 92 of the secondary winding L72. This center tap is connected to ground through a capacitor C94 and is connected to a terminal 96 of the power supply upon which an adjustable negative voltage is present of such value as completely or partially to cut off the triodes 74 and 76, this connection to the terminal 96 being through a relatively high value resistor R98. The value of the resistor R90 is much less than that of the resistor R98. The voltage division efiected by these resistors is such that the triodes 74 and 76 are, when no key is depressed, in the condition to conduct the signal at the maximum desired amplitude.

Upon depression of a playing key 34 (switch 45 being open), plate current is conducted through the relay winding L42, energizing the latter, and through the low value resistor R38 and capacitor C40 provide an initial surge of plate current to insure fast starting of the oscillator. Also, during this starting instant and thereafter plate current is supplied to the oscillator through higher value load resistor R36. Immediately upon the commencement of oscillation the output of the oscillator associated with the depressed key will be impressed upon the output collector conductor 53. Signals of a' string-like quality conductor 58, the signal being of string or flute quality, or both, depending upon the positions of the switches 60- and 64. Thus, immediately upon depression of the key the signal is transmitted through the control triodes 74 and 76 and translated into sound by the speaker 84. However, due to the operation of the relay 44 and the moving of its contactor 88 to open (dotted line) position, the potential on the control grids of triodes 74 and 76 commences being reduced as the capacitor C94 is discharged through resistor R98 which, it will be recalled, is connected to the terminal 96, the potential on which is such as to increase the bias on triodes 74 and 76 substantially, thereby greatly to reduce the amplitude of the conducted signal, and, if the potential on terminal 96 is adjusted to cut-off value, to reduce the signal amplitude to zero. The time constant of this circuit is preferably such as to cause fairly rapid decay of the tone and may be designed so that the tone intensity envelope will simulate that of a plucked string, marimba, or may have a longer time constant to simulate the tone intensity envelopes of bells and chimes. Upon release of the key the relay 44 is deenergized and the conductor 88 thus returned to full line position so that the control tubes 74 and 76 are again rendered conductive almost instantly due to the relatively low value of resistor R90. 7

It may be noted that the instrument must be played in a non-legato or detached manner in order to obtain the percussion eifect. When this elfect is not desired the switch 45 is manually closed thereby preventing operation of the relay 44. Because the triodes 74 and 76 are, when no key is depressed, biased to conduct the signal at the maximum desired amplitude, the tones produced have a sharp rapid percussion attack and longer decay. Such tones are musically useful in accenting certain passages of a musical score being played by an orchestra, emphasizing the rhythm or solo part, and otherwise introducing variety in the rendition of the music. It will be understood that various quality, volume, and expression controls, and the like, as are customary in electrical musical instruments will be provided. Such controls are disclosed in my prior Patent 2,645,968, granted June 21, 1953.

In lieu of the output system of the instrument shown in Fig. 1, an output system such as shown in Fig. 2 may be employed. Such parts of the apparatus as correspond to those clescribed with reference to Fig. 1 have corresponding reference characters applied thereto, and the description thereof will not be repeated. In this embodiment of the invention the relay 44 operates a normally open contactor 100 which, upon energization of the relay, connects a conductor 102 to ground.

A potential of approximately +37 volts is maintained on conductor 102 by a voltage divider comprising resistors R104 and R106 connected in series between a +250 v. terminal of the power supply and ground. This potential is opposed by a potential of approximately 30 volts generated across a resistor R108 of an ungrounded power supply. This power supply comprises a diode 110 having its plate connected to one terminal of a secondary winding L112 of the power supply transformer 114'. The other terminal of the secondary winding L112 is connected to terminal 144 which in turn is connected to the cathode of the diode 110 by a capacitor C116 which is in parallel with the resistor R108. The terminal 114 is connected by a low value resistor R118 to the anodes of diodes 120 and 122. The cathode of diode 122 is connected to a v. terminal of the power supply and operates as a voltage regulator to prevent the potential on the plates of these diodes from exceeding +5 volts. This voltage also appears upon the cathode of diode 120 which is connected to the center tap 92 of secondary winding L72 by a conductor 126. The conductor 126 is connected to a 30 v. terminal of the power supply by a resistor R128 of relatively high value and may additionally be connected to this terminal through a resistor R130 of relatively low value upon closure of a manually operated switch 132. The conductor 102 is connected to the cathodes of triodes 74 and 76 through series connected resistors R134 and R135 the junction of these resistors being connected to ground by a capacitor C136. Through this circuitry the cathodes are normally maintained at a potential close to +37 volts while the grids of these triodes are maintained at a potential of approximately +5 volts. However, upon energization of the relay 44 its conductor 100 closes to connect conductor 102 to ground which potential is almost immediately impressed on the cathodes of the triodes 74 76 thus rendering them conductive. Lowering the potential on conductor 1102 to substantially ground renders the diodes 120 and 122 non-conductive and as a result the capacitor C94 gradually discharges through resistor R123 until the potential on the center tap 92 approaches +30 volts which is sufiicient to bias the triodes 74 and 76 beyond cutoff. The rate of discharge of the capacitor C94, and hence the rate of decay of a tone may be increased by closing switch 132 sothat the resistance of the path through the capacitor C94 can discharge is substantially lessened. As soon as the playing key is released and the relay 44 deenergized the potential on conductor 102 is immediately raised to approximately +37 volts and the system is thus reconditioned for operation upon depression of the next key.

While I have shown and described a particular embodiment of my invention, it will be apparent to those skilled in the art that numerous modifications and variations may be made in the form and construction thereof, without departing from the more fundamental principles of the invention. I therefore desire, by the following claims, to include within the scope of my invention all such similar and modified forms of the apparatus disclosed, by which substantially the results of the invention may be obtained by substantially the same or equivalent means.

I claim:

1. In an electrical musical instrument having electron discharge device oscillators for the generation of musical tone signals, said oscillators being normally non-oscillating and being caused to oscillate by supplying current thereto, playing keys, a current supply conductor common to all the oscillators, switches operated by the keys to connect said conductor to the oscillators respectively, a source of electric energy, a relay having a winding, means connecting said winding between said conductor and the source of electrical energy, an output system coupled to the oscillators to receive the tone signals generated thereby and including amplitude control means responsive to the bias potential supplied thereto, biasing means forming part of the control means and biasing said control means to transmit tone signals at high amplitude, and means interposed in the biasing means controlled by the relay, upon energization thereof when a key operated switch is closed, to cause a gradual change in the bias on the control means in a sense to effect a reduction in the amplitude of the signals transmitted, thereby to cause the tone to be produced with a percussive intensity envelope.

2. In an electrical musical instrument having electron discharge device oscillators for the generation of electrical musical tone signals, said oscillators being normally non-oscillating and being caused to oscillate by supplying current thereto, playing keys, a current supply conductor common to all the oscillators, switches operated by the keys to connect said conductor to the oscillators respectively, a source of electric energy, a relay having a winding, means connecting said Winding between said conductor and one terminal of the source of electrical energy, return conductors from the oscillators to the other terminal of the source, an output system coupled to the oscillators to receive the tone signals generated thereby and including amplitude control means responsive, to the bias potential supplied thereto, biasing means forming part of the control means and normally biasing said control means to transmit tone signals at high amplitude, and means interposed in the biasing means controlled by the relay, upon energization thereof when a key operated switch is closed, to cause a gradual change in the bias on the control means in a sense to effect a reduction in the amplitude of the signals transmitted, thereby to cause the tone to be produced with a percussive intensity envelope.

3. In an electrical musical instrument having electron discharge device oscillators for the generation of musical tone signals, said oscillators being normally non-oscillating and being caused to oscillate by supplying current thereto, playing keys, a current supply conductor common. to all the oscillators, switches operated by the keys to connect said conductor to the oscillators respectively, a source of electric energy, a relay having a winding, means connecting said winding between said conductor and the source of electrical energy, an output system coupled to the oscillators to receive the tone signals generated thereby and including means responsive to the bias potential supplied thereto, and means interposed in the amplitude control means controlled by the relay, upon energization thereof when a key operated switch is closed, to change the bias potential supplied to the control means to a value to cause high amplitude transmission of the signal through the control means to the output system, and means forming part of the control means and operable immediately after the bias on the control means has caused the transmission of the signal at high amplitude, to cause a gradual change in the bias on the 6 control means in a sense to effect a reduction of the aniplitude of the signals transmitted thereby to a low amplitude, thereby to cause the tone to be produced with a percussive intensity envelope.

References Cited in the file of this patent UNITED STATES PATENTS 

